Hands-On Design Patterns with Swift

ViewModel

ViewModel, as mentioned previously, is meant to provide a usable representation of Model to the View layer. It will also provide a way to bind itself to events. In Swift, we can use closures, in order to attach the callbacks to ViewModel:

class ViewModel {

Other solutions, including two-way data binding, Observables, and Functional Reactive Programming, provide abstractions over the manual binding example that we'll be performing here. If you were to use MVVM extensively, I'd recommend that you properly leveraged two-way data binding.

Similar to ApplicationController in the MVC pattern, we'll keep track of the main Model manager, which is the QuestionController in ViewModel:

    private let questions = QuestionController()

Keeping ...